A drug that costs just 25 cents a day could change the lives of millions of people with irritable bowel syndrome, according to research.
Amitriptyline was found to significantly improve symptoms of the debilitating condition, which affects up to 13 million Britons and 30 million Americans.
Experts said low doses of antidepressants, which are used to treat a range of conditions from nerve pain to migraine prevention, should also be prescribed for irritable bowel syndrome (IBS).
In the first trial of its kind, British researchers wanted to test whether low doses of the antidepressant could benefit IBS patients in a community setting.
Amitriptyline, pictured, made people twice as likely to report an overall improvement in IBS symptoms after six months than those taking fake drugs
Around 463 patients were recruited from 55 GP practices in West Yorkshire, Wessex and West England, with half given amitriptyline and the other half a placebo.
Patients checked how many tablets of the trial medication they took based on a score determined based on their IBS symptoms and any side effects.
Those who took amitriptyline were almost twice as likely to report an overall improvement in IBS symptoms after six months than those who took dummy drugs.
Researchers from the universities of Leeds, Southampton and Bristol also tracked participants’ anxiety or depression scores.
They found that these were not changed – suggesting that the beneficial effects of the medication were through the gut, and not due to any effect as an antidepressant.
Affecting around one in twenty people worldwide, IBS causes aching pain, bloating, diarrhea and constipation – and there are few effective treatments available.
The long-term condition, for which there is no known cure, can have a substantial impact on patients’ quality of life and ability to work and socialize.
Amitriptyline belongs to a group of medications called tricyclics, which were originally used in high doses to treat depression.
But the drug is also thought to act directly on the nerves in the intestine, which has an effect on digestive problems.
Compounds called neurotransmitters, which are found in the brain and are responsible for regulating mood, are also present in the nerves of the digestive system.
Previous small studies of low-dose tricyclic antidepressants for IBS suggested a possible benefit in patients seen in hospital clinics who often have more difficult to treat symptoms.
But this new study, published in the Lancet, is the first to examine its use for IBS in primary care.
The NICE guidelines state that antidepressants can be used to treat the condition if other options have failed, but doctors are often reluctant.
Researchers hope the findings will be reassuring to GPs, alongside new proposed dosing guidelines.
Alexander Ford, Professor of Gastroenterology at the University of Leeds School of Medicine, said: ‘Amitriptyline is an effective treatment for IBS and is safe and well tolerated.
IBS affects about one in twenty people worldwide and there are not many treatments available
‘This new, rigorously conducted study indicates that GPs should support primary care patients in trying low-dose amitriptyline if their IBS symptoms have not improved with recommended first-line treatments.’
Professor Andrew Farmer from the National Institute for Health and Care Research said: ‘The results of this study are hugely encouraging.
‘It shows that a drug already widely available to treat a number of other conditions appears to be safe and effective for people with IBS.’